1. Field of the Invention
The present invention relates to a method and apparatus for inserting stickers (or “slats”) between layers (or “courses”) of lumber or other materials. More particularly, the principles of the present invention may assist in creating a material package that is ready for subsequent handling and/or shipping; for example, for further processing or delivery to a downstream user. Principles of the present invention also relate to a method and apparatus for identifying defective stickers, as well as a method and apparatus for removing defective stickers from a sticker placer.
2. Related Art
For manufacturing materials (such as lumber or other materials) that need to be dried, slats are typically inserted between layers of the material to allow for improved airflow between the layers and therefore permit better drying. When inserting slats, it is generally important to position the slats at closely held vertical positions in relation to the material layers. It is also generally important for the slat placing machinery to be able to keep up with the slat feeding machinery as well as the rest of the material stacking machinery.
In lumber manufacturing sawmills in particular, the operating speed of conventional equipment for feeding material layers to lumber stackers has been increased. Unfortunately, this has resulted in bottlenecks and inefficiencies at the stacker/slat layer machinery. The industry is therefore in need of a method and apparatus that permits stickers (also referred to as “slats” or “spacers”) to be positioned between layers of material at an increased rate.
Conventionally, a “stickered” package of lumber is created by arranging a set of slat magazines over the layers of lumber being stacked and by dropping or placing a set of slats from the slat magazines onto the top layer either manually or automatically. Conventional single-carriage slat insertion type machines also exist that place the slats between the layers being stacked. The process of placing or dropping slats on the top layer is typically repeated as the lumber is stacked until the desired number of courses has been set and a full stickered package has been created.
Lumber is generally 4′ to 28′ in length, 1″ to 6″ in thickness, and 3″ to 15″ in width. This lumber is conventionally gathered and formulated into packages ranging from 42″ to 120″ in width and 50 to 75 layers high, or more. These packages require robust machinery to stack the lumber courses and arrange slats between the layers in an efficient manner at a very high speed. Efficient operation also requires a balance of low maintenance and minimal tuning during operation. Maintaining maximum “up time” enables maximum overall production output. It would therefore be desirable to have a high speed sticker placer that provides a reliable, accurate, and low maintenance mechanism for placing slats between layers.
Additionally, conventional sticker placers lack the ability to effectively identify and eliminate defective slats from the process. Defective slats can create problems in the machinery, including jamming or ineffective slat placement. Such problems also require increased manual intervention and increase maintenance and down-time. It would also be desirable, therefore, to have a method and apparatus for eliminating the presence of defective slats before placement in the material package.